JP4472044B2 - Method for producing polymer aggregate - Google Patents

Description

【００３４】
【表２】

【００３５】
【表３】

【００３６】
【発明の効果】
本発明の製造方法によれば、乳化重合により得られる重合体ラテックスから凍結溶融法により重合体凝集物を回収するに際し、乳化剤が原因で発生する泡によって重合体凝集物が浮上するのを防止して、生産性および工程通過性を低下させることなく、品質の良好な重合体凝集物を製造することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a polymer aggregate from a polymer latex obtained by emulsion polymerization.
[0002]
[Prior art]
In order to recover the polymer from the latex of the polymer obtained by emulsion polymerization, the polymer is generally agglomerated or coagulated to a size of several tens to several hundreds of μm, and the polymer is subjected to washing, dehydration and drying steps. The method of collecting as powder is taken.
A freeze-thaw method is known as one of the methods for agglomerating or coagulating a polymer contained in latex. In this method, the polymer latex is frozen and then melted, and this operation forms a slurry of polymer aggregates. Since part of the emulsifier used in the emulsion polymerization is present in the aqueous system of the slurry, foaming may occur due to stirring or the like, and the polymer aggregate may float. When the polymer aggregates float, it interferes with the recovery of unfloated polymer aggregates, not only significantly impairs productivity and processability, but also reduces the cleaning effect of the polymer and easily contains impurities. Therefore, it is difficult to maintain the quality at a high level, which is not preferable.
[0003]
[Problems to be solved by the invention]
The present invention solves the problem that polymer agglomerates in a slurry that cannot be solved by a conventional method when a polymer latex is aggregated by freezing and thawing a polymer latex obtained by emulsion polymerization. Another object of the present invention is to provide a method for improving the productivity and processability during the recovery of polymer aggregates and obtaining polymer aggregates of better quality.
[0004]
[Means for Solving the Problems]
As a result of intensive studies in view of the current situation, the present inventors have
The polymer latex obtained by emulsion polymerization is frozen, the polymer latex after freezing is melted to obtain a slurry containing polymer aggregates, and at the time of melting, 0.01 to An antifoaming agent comprising 1% by weight of an alkaline earth metal salt and 0.01 to 1% by weight of a silicone-based antifoaming agent or a nonionic surfactant is added, and the temperature of the slurry is kept at 20 ° C to 95 ° C; Next, a method for producing a polymer aggregate characterized by dehydrating , wherein the polymer latex is
(1) A multilayer structure graft polymer having one or more rubber layers mainly composed of a polymer of alkyl acrylate and having one or more resin layers mainly composed of a polymer of alkyl methacrylate as an outermost layer. Containing latex;
(2) A multilayer structure graft polymer having one or more rubber layers mainly composed of a polymer of a diene vinyl compound, and having one or more resin layers mainly composed of a polymer of alkyl methacrylate as the outermost layer. Containing latex; and
(3) Latex mainly composed of a polymer of alkyl methacrylate ester;
A method for producing a polymer aggregate, which is one latex selected from the group consisting of two or more mixed latexes , and prevents the polymer aggregate from floating in the slurry and impairs the quality of the polymer. The present inventors have found that polymer aggregates can be obtained without arriving at the invention.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
The present invention can be applied to a latex in which a fine polymer having a particle diameter of 0.01 to 1 μm obtained by emulsion polymerization is dispersed.
The latex of the polymer to which the method of the present invention is applied is a latex in which a polymer having a solid property at room temperature is dispersed, specifically, one or more selected from the monomers exemplified below. A latex in which a polymer obtained by homopolymerization, copolymerization or graft polymerization is dispersed, or a mixed latex thereof. Examples of the monomer include acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-methacrylic acid 2- Methacrylic acid esters such as ethylhexyl; Aromatic vinyl compounds such as styrene, monochlorostyrene, dichlorostyrene, α-methylstyrene; N-isopropylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-o-chlorophenylmaleimide, etc. N-substituted maleimide compounds; vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride, vinyl bromide and vinyl fluoride; vinylidene halides such as vinylidene chloride, vinylidene bromide and vinylidene fluoride Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid and maleic acid; alkenes such as ethylene, propylene, isoprene and 1,3-butadiene; chloroprene, vinyl acetate, vinyl benzoate, allyl (meth) acrylate, Examples thereof include polyfunctional monomers such as diallyl phthalate, triallyl cyanurate, monoethylene glycol di (meth) acrylate, polyethylene glycol (meth) acrylate, divinylbenzene and glycidyl (meth) acrylate.
[0006]
When the method of the present invention is applied to a latex containing a polymer having excellent transparency as described below, a polymer having extremely excellent optical properties can be obtained, which is recommended.
(1) A multilayer structure graft polymer having one or more rubber layers mainly composed of a polymer of alkyl acrylate and having one or more resin layers mainly composed of a polymer of alkyl methacrylate as an outermost layer. Contains latex. (2) A multilayer structure graft polymer having one or more rubber layers mainly composed of a polymer of a diene vinyl compound, and having one or more resin layers mainly composed of a polymer of alkyl methacrylate as the outermost layer. Contains latex. (3) A latex mainly composed of a polymer of alkyl methacrylate. Any mixed latex of (1) to (3).
[0007]
In the present invention, there are no particular restrictions on the emulsion polymerization conditions such as the type and amount of polymerization initiator, emulsifier, chain transfer agent, etc. used in emulsion polymerization to obtain latex, polymerization temperature, monomer dropping method and the like. The emulsion polymerization conditions that have been widely used conventionally can be used.
[0008]
Examples of polymerization initiators include inorganic peroxides such as potassium persulfate, water-soluble redox initiators such as ammonium persulfate-acidic sodium sulfite, and oil-soluble redox initiators such as cumene hydroperoxide-sodium formaldehyde sulfoxylate. Can be used.
[0009]
As an emulsifier, anionic surfactants such as carboxylates such as sodium stearate, sulfonic acids such as dodecylbenzenesulfonic acid or salts thereof, and organic and inorganic acid ester salts such as sodium lauroyl sarcosine and sodium lauryl sulfate Can be preferably used, but if necessary, a cationic surfactant and a nonionic surfactant can be used in combination.
[0010]
Moreover, as a chain transfer agent used as needed, mercaptans, such as n-octyl mercaptan, can be mentioned. Further, if desired, emulsion polymerization can be carried out by adding known additives such as ultraviolet absorbers and dyes to the monomer.
The solid content of the latex is usually 10 to 60% by weight, preferably 20 to 50% by weight.
[0011]
In the present invention, the polymer latex is first frozen by any method. There are no particular restrictions on the freezing conditions and the operating method. Next, when the frozen latex is thawed, a slurry containing polymer aggregates is obtained. In this case, the solid content of the polymer in the slurry is preferably 3 to 50% by weight, more preferably 5 to 30% by weight. If the solid content is less than 3% by weight, the productivity is lowered, which is not preferable. On the other hand, if the solid content exceeds 50% by weight, the slurry viscosity is increased and the handling property of the slurry is deteriorated.
[0012]
The frozen latex is usually melted by introducing the latex into a dispersion medium that has been heated in advance. A typical example of a dispersion medium that can be used for this purpose is deionized water.
[0013]
In the present invention, the metal salt and the antifoaming agent may be added directly to the slurry containing the polymer aggregates or may be added to the dispersion medium used when melting the frozen latex. Therefore, it is sufficient that the metal salt and the antifoaming agent are present in the slurry containing the finally obtained polymer aggregate, which not only suppresses the floating of the polymer aggregate but also reduces the weight. A polymer aggregate can be obtained without impairing the quality of the coalescence.
[0014]
Metal salt used in the present invention is a water-soluble salt, and examples thereof include hydrochloric acid, nitric acid, gold Shokushio inorganic acids such as sulfuric acid; include formic acid, acetic acid, gold Shokushio of organic acids such as oxalic acid it is, for example, may be mentioned calcium chloride, calcium nitrate, the magnesium sulfate and the like. The good Masui as a metal salt of calcium sulfate, a calcium chloride and magnesium sulfate, particularly preferred are calcium chloride and magnesium sulfate. These metal salts may be used alone or in combination of two or more.
[0015]
In the present invention, the addition amount of the metal salt is 0.01 to 1% by weight, preferably 0.05 to 0.5% by weight, based on the weight of the polymer. If the addition amount is less than 0.01% by weight, the effect of preventing the polymer aggregates from floating is not sufficient, which is not preferable. On the other hand, if the addition amount exceeds 1% by weight, a large amount of metal salt remains in the finally obtained polymer powder, which often leads to coloring and a decrease in hot water whitening resistance.
The antifoaming agent used in the present invention has an antifoaming function, and examples thereof include silicone-based antifoaming agents and nonionic surfactants. An antifoamer may be used independently or may use 2 or more types together.
[0016]
The silicone-based antifoaming agent is, for example, a so-called “silicone defoaming agent”, “silicone antifoaming agent”, “silicone non-foaming agent” or “silicone defoaming agent”, and these are commonly used. Contains polydiorganosiloxane and silica. The silicone-based antifoaming agent used in the present invention does not necessarily need to contain polydiorganosiloxane and silica, and a silicone-based antifoaming agent containing other components can also be used.
[0017]
The form of the silicone antifoam are known various ones, such as those made of silicone oil, and viscous compound was added carbon black in a silicone oil, alumina, inorganic fine powder such as Koroidarushi Li Ca The oil compound (oil compound), the oil compound dissolved in an organic solvent, the oil compound made into an oil-in-water emulsion with a surfactant, and the like are known. In the present invention, any of these known silicone antifoaming agents can be used, but it is preferable to use a type in which an oil compound is made into an oil-in-water emulsion with a surfactant. These silicone antifoaming agents may be used alone or in combination of two or more.
[0018]
The nonionic surfactant used in the present invention includes a low HLB nonionic surfactant and a polymer mainly composed of propylene oxide.
The low HLB nonionic surfactant is a nonionic surfactant having an HLB of 10 or less, preferably 5 or less. Specific examples thereof include sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, sorbitan trioleate. And polyoxyethylene alkyl ether and polyoxyethylene nonylphenyl ether having 5 to 10 ethylene oxide addition moles. Specific examples of the polymer having propylene oxide as a main component include polyoxypropylene polymers and polyoxypropylene polyoxyethylene copolymers obtained by copolymerizing propylene oxide with ethylene oxide. These nonionic surfactants may be used alone or in combination of two or more.
[0019]
In the present invention, the addition amount of the antifoaming agent is 0.01% by weight to 1% by weight, preferably 0.05% by weight to 0.5% by weight, based on the weight of the polymer in the slurry. If the addition amount is less than 0.01% by weight, the effect of preventing the polymer aggregates from floating is not sufficient, which is not preferable. On the other hand, if the amount added exceeds 1% by weight, a large amount of antifoaming agent may remain in the finally obtained polymer powder, leading to deterioration of the properties of the polymer.
In the present invention, the silicone-based antifoaming agent and the nonionic surfactant may be used alone or in combination.
[0020]
In the present invention, the temperature of the slurry is preferably maintained at 20 ° C to 95 ° C, and more preferably 30 ° C to 90 ° C. If it is less than 20 ° C., the cohesive force of the polymer particles is lowered, and the aggregated particles are easily crushed in the subsequent washing and dehydration steps, which is not preferable. When the slurry temperature exceeds 95 ° C., blocking tends to occur, which is not preferable.
[0021]
The polymer aggregate slurry containing the metal salt and antifoaming agent is then dewatered. For the dehydration, a bucket-type or decanter-type centrifuge can be used.
The slurry after dehydration is dried to obtain polymer aggregate powder. For drying, a fluid dryer, a vibration dryer, a hot air dryer or the like can be used.
[0022]
In the polymer aggregate obtained by the present invention, known additives such as an anti-sticking agent, an ultraviolet absorber, a lubricant, an antioxidant and a dye can be blended according to the purpose of use.
[0023]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by these.
“Parts” and “%” used in the following examples and comparative examples are all “parts by weight” and “% by weight”. Moreover, the physical property evaluation of the test piece in an Example and a comparative example was performed with the following method.
Measurement of particle diameter The particle diameter was measured using a light scattering photometer DLS-600 manufactured by Otsuka Electronics Co., Ltd.
(2) Slurry property 300 ml of the slurry containing aggregates was put into a measuring cylinder having an internal volume of 500 ml, sealed with a rubber stopper, and then rotated 180 degrees at intervals of 1 second, and then allowed to stand. After the elapse of 5 minutes, the floated material volume Wf (ml), the supernatant liquid volume Ww (ml) and the sediment volume Wp (ml) were measured to evaluate the foamability and sedimentation of the slurry. The smaller the foam volume and the larger the sediment volume, the better the slurry properties.
(3) Measurement of particle size 200 g of polymer aggregate powder was classified with a standard sieve, and the weight average particle size was defined as the average particle size.
(4) A 3 mm thick flat plate made by hot water whitening-resistant injection molding is immersed in warm water at 80 ° C. for 6 hours, then immersed in distilled water at room temperature, taken out after cooling to room temperature, and the surface moisture is removed with gauze. The light transmittance (visible light: 600 nm) after wiping hot water immersion was measured.
[0024]
Examples 1 to 3 and Comparative Examples 1 to 3
[1] In a reactor equipped with a stirrer, a thermometer, a nitrogen gas introduction part, a monomer introduction pipe and a reflux condenser, 150 parts of deionized water, 2 parts of sodium dodecylbenzenesulfonate and 0.05 parts of sodium carbonate And the inside of the container was sufficiently replaced with nitrogen gas to make it substantially free of oxygen, and then the internal temperature was set to 80 ° C. Thereto was added 0.015 part of potassium persulfate, and after stirring for 5 minutes, a monomer mixture consisting of 14.67 parts of methyl methacrylate, 0.3 part of n-butyl acrylate and 0.03 part of allyl methacrylate. Was continuously added dropwise over 20 minutes, and after completion of the addition, the polymerization reaction was further carried out for 30 minutes so that the polymerization rate was 98% or more.
[2] Next, 0.03 part of potassium persulfate was charged into the reactor and stirred for 5 minutes, and then 1.6 parts of methyl methacrylate, 27.9 parts of n-butyl acrylate and 0. A monomer mixture consisting of 6 parts was continuously added dropwise over 40 minutes, and after completion of the addition, a polymerization reaction was further carried out for 30 minutes so that the polymerization rate was 98% or more.
[3] Next, 0.055 parts of potassium persulfate was added to the reactor and stirred for 5 minutes, and then 53.9 parts of methyl methacrylate, 1.1 parts of n-butyl acrylate and n-octyl were used. A monomer mixture containing 0.5 part of mercaptan (chain transfer agent) is continuously added dropwise over 100 minutes, and after completion of addition, a polymerization reaction is further performed for 60 minutes so that the polymerization rate is 98% or more. A latex containing the multilayer structure polymer 1 was obtained. The particle size was 0.09 μm.
[0025]
Next, 10 kg of latex containing the obtained multilayer structure polymer 1 was frozen in a −30 ° C. freezer. There were no unfrozen parts. Thereafter, 10 kg of deionized water was charged into a dissolving tank equipped with a stirrer, a thermometer and a jacket. Deionized water is heated up to 80 ° C., and when the deionized water reaches that temperature, the metal salt and antifoaming agent shown in Table 1 are added thereto, and then the frozen latex is added thereto. And dissolved into a slurry. Furthermore, this slurry was kept at 80 ° C. for 10 minutes for heat treatment. Further, a small amount of this slurry was extracted to examine the properties of the latex.
Subsequently, the slurry was taken out, dehydrated and washed with a centrifuge, and then dried with a circulation dryer at 70 ° C. The weight average particle diameter of the obtained polymer aggregate was determined. Next, the polymer aggregates after drying were extruded into pellets by an extruder, a flat plate having a thickness of 3 mm was formed by an injection molding machine, and a hot water whitening test was performed. These results are shown in Table 1.
[0026]
Examples 4-6 and Comparative Examples 4 and 5
[1] A reactor equipped with a stirrer, thermometer, nitrogen gas inlet, monomer inlet tube and reflux condenser was charged with 150 parts of deionized water, 3 parts of sodium stearate and 0.05 part of sodium carbonate. After the inside of the container was sufficiently replaced with nitrogen gas to make it substantially free of oxygen, the internal temperature was set to 80 ° C. Thereto was added 0.04 part of potassium persulfate, and after stirring for 5 minutes, it was composed of 11.2 parts of methyl methacrylate, 24 parts of n-butyl acrylate, 4.6 parts of styrene and 0.2 part of allyl methacrylate. The monomer mixture was continuously added dropwise over 60 minutes, and after completion of the addition, a polymerization reaction was further performed for 30 minutes so that the polymerization rate was 98% or more.
[2] Next, 0.02 part of potassium persulfate was charged into the reactor and stirred for 5 minutes, and then 0.8 part of methyl methacrylate, 16 parts of n-butyl acrylate, 3.1 parts of styrene, A monomer mixture consisting of 0.1 part of allyl methacrylate was continuously supplied dropwise over 30 minutes, and after completion of the addition, a polymerization reaction was further carried out for 30 minutes so that the polymerization rate was 98% or more.
[3] Next, 0.04 part of potassium persulfate was put into the reactor and stirred for 5 minutes, and then 37.7 parts of methyl methacrylate, 2 parts of n-butyl acrylate and n-octyl mercaptan ( (Chain transfer agent) A monomer mixture containing 0.3 part is continuously added dropwise over 100 minutes, and after completion of the addition, a polymerization reaction is further performed for 60 minutes so that the polymerization rate becomes 98% or more. A latex containing structural polymer II was obtained. The particle diameter was 0.12 μm.
[0027]
Next, 10 kg of the latex containing the obtained multilayer structure polymer II was frozen in a −30 ° C. freezer. There were no unfrozen parts. Thereafter, 10 kg of deionized water was charged into a dissolving tank equipped with a stirrer, a thermometer and a jacket. The deionized water is heated up to 40 ° C., and when the deionized water reaches this temperature, the metal salt and antifoaming agent shown in Table 2 are added, and then the frozen latex is added and dissolved therein. A slurry was obtained. Furthermore, this slurry was kept at 40 ° C. for 10 minutes for heat treatment. Further, a small amount of this slurry was extracted to examine the latex properties.
[0028]
Subsequently, the slurry was taken out, dehydrated and washed with a centrifuge, and then dried with a circulation dryer at 40 ° C. The weight average particle diameter of the obtained polymer aggregate was determined. Next, the polymer aggregates after drying were extruded into pellets by an extruder, a flat plate having a thickness of 3 mm was formed by an injection molding machine, and a hot water whitening test was performed. These results are shown in Table 2.
[0029]
Examples 7-9 and Comparative Examples 6 and 7
(1) Production of multilayer structure polymer (III-1) latex
[1] In a reactor equipped with a stirrer, a thermometer, a nitrogen gas inlet, a monomer inlet tube and a reflux condenser, 150 parts of deionized water, 3 parts of sodium dioctylsulfosuccinate and 0.05 parts of sodium carbonate were added. After charging and fully replacing the inside of the container with nitrogen gas to make it substantially free of oxygen, the internal temperature was set to 85 ° C. Thereto, a monomer mixture consisting of 33 parts of methyl methacrylate, 2 parts of methyl acrylate and 0.15 part of allyl methacrylate and 0.035 part of potassium persulfate were charged and reacted for 60 minutes to complete the polymerization reaction.
[2] Next, 0.046 part of potassium persulfate was put into the reactor and stirred for 5 minutes, and then composed of 36.5 parts of n-butyl acrylate, 8.5 parts of styrene, and 1 part of allyl methacrylate. The monomer mixture was continuously added dropwise over 60 minutes, and after completion of the addition, a polymerization reaction was further performed for 60 minutes so that the polymerization rate was 98% or more.
[3] Next, 0.02 part of potassium persulfate was put into the reactor and stirred for 5 minutes, and then 19 parts of methyl methacrylate, 1 part of methyl acrylate and n-octyl mercaptan (chain transfer agent) A monomer mixture containing 0.05 parts is continuously supplied dropwise over 40 minutes, and after the addition is completed, a polymerization reaction is further performed for 60 minutes so that the polymerization rate becomes 98% or more. A latex containing III-1) was obtained. The particle size was 0.23 μm.
[0030]
(2) Production of rigid thermoplastic polymer (III-2) latex
[1] In a reactor equipped with a stirrer, a thermometer, a nitrogen gas introduction part, a monomer introduction pipe and a reflux condenser, 200 parts of deionized water, 4 parts of sodium dioctylsulfosuccinate and 0.05 parts of sodium carbonate were added. After charging and fully replacing the inside of the container with nitrogen gas to make it substantially free of oxygen, the internal temperature was set to 80 ° C. A monomer mixture consisting of 18 parts of methyl methacrylate, 2 parts of ethyl acrylate, 0.05 part of n-octyl mercaptan (chain transfer agent) and 0.02 part of potassium persulfate were charged and reacted for 40 minutes. The polymerization reaction was complete.
[2] Next, 0.08 part of potassium persulfate was charged into the reactor and stirred for 5 minutes, and then a monomer mixture consisting of 72 parts of methyl methacrylate and 8 parts of ethyl acrylate was added over 90 minutes. The solution was continuously added dropwise, and after completion of the addition, a polymerization reaction was further performed for 60 minutes so that the polymerization rate became 98% or more to obtain a latex containing the hard thermoplastic polymer (III-2). The particle size was 0.07 μm.
The multilayer structure latex (III-1) and the rigid thermoplastic polymer (III-2) latex thus obtained are converted into a polymer equivalent of 80 parts of the multilayer structure latex (III-1) and the rigid thermoplastic polymer. (III-2) 20 parts of latex was uniformly mixed in a latex state to obtain a mixed latex.
[0031]
Next, 10 kg of the obtained mixed latex was frozen in a −30 ° C. freezer. There were no unfrozen parts. Thereafter, 10 kg of deionized water was charged into a dissolving tank equipped with a stirrer, a thermometer and a jacket. The deionized water was heated to 90 ° C., and when the deionized water reached that temperature, the metal salt and antifoaming agent shown in Table 3 were added, and the frozen latex was added and dissolved to form a slurry. Furthermore, this slurry was held at 90 ° C. for 10 minutes and subjected to heat treatment. Further, a small amount of this slurry was extracted to examine the properties of the latex.
[0032]
Subsequently, this slurry was taken out, dehydrated and washed with a centrifuge, and then dried with a circulation dryer at 80 ° C. The weight average particle diameter of the obtained polymer aggregate was determined. Next, the polymer aggregate after drying was extruded into pellets by an extruder, a 3 mm-thick flat plate was formed by an injection molding machine, and a hot water whitening test was performed. These results are shown in Table 3.
[0033]
[Table 1]

[0034]
[Table 2]

[0035]
[Table 3]

[0036]
【The invention's effect】
According to the production method of the present invention, when polymer aggregates are recovered from a polymer latex obtained by emulsion polymerization by a freeze-thaw method, the polymer aggregates are prevented from floating due to bubbles generated due to an emulsifier. Thus, a polymer aggregate having a good quality can be produced without reducing the productivity and process passability.

Claims (2)

The polymer latex obtained by emulsion polymerization is frozen, the polymer latex after freezing is melted to obtain a slurry containing polymer aggregates, and at the time of melting, 0.01 to An antifoaming agent comprising 1% by weight of an alkaline earth metal salt and 0.01 to 1% by weight of a silicone-based antifoaming agent or a nonionic surfactant is added, and the temperature of the slurry is kept at 20 ° C to 95 ° C; Next, a method for producing a polymer aggregate characterized by dehydrating, wherein the polymer latex is
(1) A multilayer structure graft polymer having one or more rubber layers mainly composed of a polymer of alkyl acrylate and having one or more resin layers mainly composed of a polymer of alkyl methacrylate as an outermost layer. Containing latex;
(2) A multilayer structure graft polymer having one or more rubber layers mainly composed of a polymer of a diene vinyl compound, and having one or more resin layers mainly composed of a polymer of alkyl methacrylate as the outermost layer. A latex containing; and (3) a latex composed mainly of a polymer of an alkyl methacrylate ester;
The manufacturing method of the polymer aggregate which is 1 type of latex chosen from these, or 2 or more types of mixed latex . The method for producing a polymer aggregate according to claim 1, wherein the antifoaming agent is a silicone-based antifoaming agent.